nohup has a terrible bad performance compared with interactive command, why?

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nohup has a terrible bad performance compared with interactive command, why?

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02-20-2009

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nohup has a terrible bad performance compared with interactive command, why?

I have a strange situation. I'm running a shell script containing several data uploads (using Oracle sqlloader utility). This script is being run on a Red Hat server.

I tried to run it in background:

$ nohup upload.sh &

This script uploads some thousands files. After several hours I checked what the nohup.out was showing and I was quite surprised to see it was very and extremely slow, because it just processed around less than a hundred files. Probably it would took more than 3 days to complete...

I ran the script interactively, I mean direct from command line showing output to screen. Surprise! the script ran several times better that when using nohup, finishing less than an hour.

I suspicted this was because the process using nohup has a slower priority than the one being run interactively. That was not true, both processes had the same priority.

Why this behaviour? I'm not a linux expert. Please help.

Thanks

viniciov

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SETUP-NSSSYSINIT(1)					     Network Security Services					       SETUP-NSSSYSINIT(1)

NAME

       setup-nsssysinit - Query or enable the nss-sysinit module

SYNOPSIS

       setup-nsssysinit [on] [off] [status]

DESCRIPTION

       setup-nsssysinit is a shell script to query the status of the nss-sysinit module and when run with root priviledge it can enable or disable
       it.

       Turns on or off the nss-sysinit module db by editing the global PKCS #11 configuration file. Displays the status. This script can be
       invoked by the user as super user. It is invoked at nss-sysinit post install time with argument on.

OPTIONS

       on
	   Turn on nss-sysinit.

       off
	   Turn on nss-sysinit.

       status
	   returns whether nss-syinit is enabled or not.

EXAMPLES

       The following example will query for the status of nss-sysinit:

		   /usr/bin/setup-nsssysinit status

       The following example, when run as superuser, will turn on nss-sysinit:

		   /usr/bin/setup-nsssysinit on

FILES

       /usr/bin/setup-nsssysinit

SEE ALSO

       pkg-config(1)

AUTHORS

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LICENSE

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